Edge interconnect self-assembly substrate

ABSTRACT

A method of forming a quilt package nodule includes forming a trench in a microchip substrate, forming a metal layer on the bottom, the first and second sides of the trench, and on a top surface of the microchip substrate proximate the first and second sides. forming a mask layer on the metal layer, removing portions of the mask and metal layers on the bottom of the trench, etching the bottom of the trench to increase the depth of the bottom of the trench, removing remaining portions of the mask layer from the metal layer to define the quilt package nodules that protrude beyond edges of the first and second sides, and removing the remaining portion of the trench bottom thereby separating the first and second sides from each other, whereupon each side includes at least one quilt package nodule protruding from the side.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.15/333,325, filed Oct. 25, 2016, which is incorporated herein byreference in its entirety, which claims the benefit of U.S. ProvisionalPatent Application Nos. 62/247,439; 62/247,457; and 62/247,477, all ofwhich were filed on Oct. 28, 2015, and all of which are incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

This application relates generally to microchips, microchips havinginterconnecting structures that are keyed to ensure assembly of themicrochips in only one orientation, and the electrical connection ofmicrochips utilizing interconnect nodules (a.k.a., quilt packaging (QP)nodules) that protrude beyond edges of microchips.

Description of Related Art

System in package (SiP) is a combination of multiple electroniccomponents of different functionality, assembled together to providemultiple functions associated with the system or sub-system. A SiPcomponent may be an active integrated circuit dye, passive components,MEMS devices, optical components as well as other packaging and devices.

Quilt packaging (QP) is a SiP chip-to-chip interconnect technology whichutilizes “nodules” that extend from, project, or protrude out fromvertical facets along edges of substrates, such as integrated circuitchips (microchips) or PCBs, to allow for inter-substrate electricalconnection, mechanical fastening, and alignment. QP technology enablesinterconnection of multiple substrates fabricated with similar ordissimilar technologies or substrate materials to be integrated into amonolithic-like structure.

Due to the nature of the QP manufacturing process, the geometry of thenodules and chips/component substrate are lithographically-defined,which allows for the application/specific definition of thesubstrate-to-substrate gap and alignment, in addition to overallpackage-level system architecture. QP is a complementary packagingapproach to existing SiP technologies, such as 3-D chip stacking andflip chip. Details regarding quilt packaging (QP) and the formation ofQP nodules can be found in U.S. Pat. No. 7,612,443 to Bernstein et al.which is incorporated herein by reference in its entirety.

Disclosed herein is a substrate assembly and a method of self-assemblyof said substrate assembly for microchips that include quilt package(QP) nodules. In addition, presented is an alternative method offabricating QP nodules through castellated protruding substrate edgefeatures.

SUMMARY OF THE INVENTION

Various preferred and non-limiting examples will now be described as setforth in the following numbered clauses:

Clause 1: A substrate assembly comprises: a first microchip including afirst interconnecting structure; and a second microchip including asecond interconnecting structure, wherein the first and secondinterconnecting structures have complementary, interlocking shapes;wherein the first interconnecting structure is interlocked with thesecond interconnecting structure.

Clause 2: The assembly of clause 1, wherein: a first material used toform a body of the first microchip also forms the first interconnectingstructure; and a second material used to form a body of the secondmicrochip also forms the second interconnecting structure.

Clause 3: The assembly of clause 1 or 2, wherein: the first material isa first semiconductor material; and the second material is a secondsemiconductor material, wherein the first and second semiconductormaterials can be the same material or different materials.

Clause 4: The assembly of any one of clauses 1-3, further comprising: afirst quilt package nodule protruding beyond an edge of the firstmicrochip; and a second quilt package nodule protruding beyond an edgeof the second microchip substrate in contact with an end or a side ofthe first quilt package nodule.

Clause 5: The assembly of any one of clauses 1-4, wherein each quiltpackage nodule is formed of electrically conductive material.

Clause 6: The assembly of any one of clauses 1-5, wherein the first andsecond microchips include respective first and second circuits, and thefirst and second quilt package nodules electrically connect the firstand second circuits.

Clause 7: The assembly of any one of clauses 1-6, wherein thecomplementary, interlocking shapes of the first and secondinterconnecting structures include at least one of the following: acurved or circular projection and a curved or circular slot or hole; apolygon shaped projection and a polygon shaped receiving slot; and at-shaped projection and a t-shaped slot.

Clause 8: The assembly of any one of clauses 1-7, wherein: the firstinterconnecting structure is a first quilt package nodule; and thesecond interconnecting structure is a second quilt package nodule.

Clause 9: The assembly of any one of clauses 1-8, wherein thecomplementary shapes of the first and second quilt package nodulesinclude at least one of the following: first and second L-shapes; aT-shape quilt package nodule and a T-shaped receiving slot; a curved orrounded projection and a curved or rounded receiving slot; astair-stepped projection and a stair-stepped receiving slot; and aV-shaped projection and a V-shaped receiving slot.

Clause 10: The assembly of any one of clauses 1-9, wherein the first andsecond interconnecting structures are keyed to ensure assembly of thefirst and second interconnecting structures in only one orientation.

Clause 11: The assembly of any one of clauses 1-10, wherein: the firstinterconnecting structure comprises a first cavity in a surface of thefirst microchip; and the second interconnecting structure comprises afirst projection on a side of the second microchip, wherein interlockingthe first interconnecting structure and the second interconnectingstructure comprises the first projection being inserted in the firstcavity.

Clause 12: The assembly of any one of clauses 1-11, wherein: the firstprojection includes a quilt package nodule protruding beyond an edge ofthe first projection; and the first cavity includes in a nodule socketconfigured to receive the quilt package nodule when the first projectionis inserted in the first cavity.

Clause 13: The assembly of any one of clauses 1-12, wherein: the firstinterconnecting structure comprises a nodule socket in the surface ofthe first microchip; and the second interconnecting structure comprisesa quilt package nodule protruding beyond an edge of a recess in the sideof the second microchip, wherein the socket is configured to receive thequilt package nodule when the first projection is inserted in the firstcavity.

Clause 14: The assembly of any one of clauses 1-13, wherein: the firstinterconnecting structure comprises a second cavity formed in thesurface of the first microchip; and the second interconnecting structurecomprises a second projection on the side of the second microchip,wherein interlocking the first interconnecting structure and the secondinterconnecting structure comprises the second projection being insertedin the second cavity.

Clause 15: The assembly of any one of clauses 1-14, wherein: the firstand second projections include first and second quilt package nodulesprotruding beyond edges of the first and second projections,respectively; and the first and second cavities include first and secondnodule sockets configured to receive the first and second quilt packagenodules when the first and second projections are inserted in the firstand second cavities.

Clause 16: A method of forming a quilt package nodule on an edge of amicrochip substrate comprises: (a) forming a trench in a microchipsubstrate, wherein the trench includes a bottom and first and secondsides; (b) following step (a), forming a metal layer on the bottom, thefirst and second sides of the trench, and on a top surface of themicrochip substrate proximate the first and second sides; (c) followingstep (b), forming a mask layer on the exposed surfaces of the metallayer; (d) following step (c), removing portions of the mask and metallayers on the bottom of the trench; (e) following step (d), etching thebottom of the trench to increase the depth of the bottom of the trench;(f) following step (e), removing remaining portions of the mask layerfrom the surfaces of the metal layer, whereupon remaining portions ofthe metal layers on the first and second sides define quilt packagenodules that protrude beyond edges of the first and second sides; and(g) following step (f), removing the remaining portion of the trenchbottom thereby separating the first and second sides from each other,whereupon each side includes at least one quilt package noduleprotruding from said side.

Clause 17: The method of clause 16, wherein each side includes aplurality of quilt package nodules that protrude beyond the edge of saidside.

Clause 18: The method of clause 16 or 17, wherein the etching of step(e) forms an undercut between the metal layers on the first and secondsides and the bottom of the trench.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an exploded top view of a substrate assembly including fourmicrochips including interconnecting structures having complementaryshapes formed in the body of each microchip, and including quiltpackaging (QP) nodules along edges of each microchip;

FIG. 1B is an assembled view of the substrate assembly shown in FIG. 1A;

FIG. 2A is an exploded view of a substrate assembly including first andsecond microchips having first and second interconnecting structures inthe form of quilt package (QP) nodules, having complementary shapes;

FIG. 2B is an assembled view of the substrate assembly shown in FIG. 2A;

FIG. 3A is an exploded view of a substrate assembly including a firstmicrochip having a number of first interconnecting structures, in theform of QP nodules, having different shapes and a second microchiphaving a number of different second interconnecting structures, in theform of QP nodules, with complementary shapes;

FIG. 3B is an assembled view of the substrate assembly shown in FIG. 3A;

FIG. 4A (left) is a top view of a microchip with cavities andcastellation sockets and FIG. 4A (right) is a side view of a microchipincluding edge castellations (including QP nodules) configured to beinserted into the castellation sockets;

FIG. 4B is an assembled view of the microchips shown in FIG. 4A takenalong line IVB-IVB in FIG. 4A;

FIG. 4C is an assembled view of the microchips shown in FIG. 4A takenalong line IVC-IVC in FIG. 4A;

FIG. 5A is a top view of a pair of microchips including QP nodulesformed in the manner described in connection with FIGS. 6A-6G;

FIG. 5B is a side view take along line VB-VB in FIG. 5A; and

FIGS. 6A-6G are views of the steps of a method for forming themicrochips including QP nodules shown in FIGS. 5A and 5B from a commonmicrochip substrate.

DESCRIPTION OF THE INVENTION

The following disclosure will be with reference to the accompanyingfigures and examples where like reference numbers correspond to like orfunctionally equivalent elements.

With reference to FIGS. 1A and 1B, a first example substrate assembly 2can include two, three, or more microchips joined by interconnectingstructures formed in the body or substrate material forming eachmicrochip. The example substrate assembly 2 shown in FIGS. 1A-1Bincludes four microchips 4, 6, 8, and 10. However, this is not to beconstrued in a limiting sense.

In this example, microchip 4 includes first and second interconnectingstructures 12 and 14 formed along different side edges thereof;microchip 6 includes first and second interconnecting structures 16 and18 formed along different side edges thereof; microchip 8 includes firstand second interconnecting structures 20 and 22 formed along differentside edges thereof; and microchip 10 includes first and secondinterconnecting structures 24 and 26 formed along different side edgesthereof.

In this example, interconnecting structures 12 and 16 have keyedcomplementary, interlocking shapes; interconnecting structures 14 and 22have keyed complementary interlocking shapes; interconnecting structures18 and 26 have keyed complementary, interlocking shapes; andinterconnecting structures 20 and 24 have keyed complementary,interlocking shapes. While each pair of interconnecting structures shownin the example substrate assembly 2 of FIGS. 1A and 1B include differentshaped keyed complementary, interlocking shapes, this is not to beconstrued in a limiting sense.

A benefit of each pair of keyed complementary, interlocking shapes isthat microchips 4, 6, 8, and 10 can only be assembled in onearrangement/orientation, as shown in FIG. 1B. In this regard, eachinterconnecting structure is only keyed to, and complementary andinterlocking with one other interconnecting structure—and isincompatible with all of the other interconnecting structures. However,this is not to be construed in a limiting sense since the use of anyshaped interconnecting structure is envisioned, provided microchips 4-10can be assembled in a suitable arrangement/orientation.

An advantage of microchips 4-10 having different keyed complementaryinterconnecting structures include the ability to assemble microchips4-10 in an automated manner via random motion 28, e.g., via vibration 28of microchips 4-10 on a suitable substrate in a manner known in the art,e.g., a vibration table.

Each interconnecting structure can include one or more quiltelectrically conductive package (QP) nodules 30 formed on one or moreedges thereof that can be used to provide electrical connectivitybetween each pair of microchips having their keyed complementary,interconnecting shapes coupled together and/or as furtherinterconnecting structures to provide mechanical stability between eachsaid pair of microchips. QP nodules 30 and the method of making QPnodules 30 is known in the art and will not be further described hereinfor simplicity. Details regarding QP nodules and one method for formingQP nodules can be found in U.S. Pat. No. 7,612,443, wherein QP nodulesare referred to as “interconnect nodules”.

As can be seen in FIG. 1B, when the first and second interconnectingstructures of each microchip 4-10 are interlocked in a manner shown inFIG. 1B, QP nodules 30 of keyed complementary, interlocking shapes canbe in contact with each other. For example, QP nodules 30-1 and 30-2 ofmicrochips 4 and 6 can be in contact; QP nodules 30-3 and 30-4 ofmicrochips 6 and 10 can be in contact; QP nodules 30-5 and 30-6 ofmicrochips 10 and 8 can be in contact; and QP nodules 30-7 and 30-8 ofmicrochips 8 and 4 can be in contact.

As can be seen, QP nodules can be part of the keyed complementaryinterlocking shapes as shown, for example, by interconnecting structures12, 16 (QP nodules 30-1 and 30-2), and 20, 24 (QP nodules 30-5 and30-6). Also or alternatively, QP nodules can be included along edges ofinterconnecting structures as shown, for example, by interconnectingstructures 18, 26 (QP nodules 30-3 and 30-4), and 14, 22 (QP nodules30-7 and 30-8). Due to ease of formation, QP nodules 30 can be desirablyformed along straight edges of microchips versus on curved or roundedsurfaces. However, this is not to be construed in a limiting sense sinceit is envisioned that QP nodules can also or alternatively be formed oncurved or rounded surfaces.

The purpose of the electrically conductive QP nodules 30 in contact witheach other when microchips 4-10 are assembled in the manner shown inFIG. 1B is to electrically connect circuitry on adjacent microchips. Forexample, circuitry 34 of microchip 4 can be electrically connected tocircuitry 36 of microchip 6 via the QP nodules 30 in contact with eachother on microchips 4 and 6. Similarly, circuitry 34 can be electricallyconnected with circuitry 38 of microchip 8 via the QP nodules 30 incontact with each other on microchips 4 and 8. Finally, circuitry 40 ofmicrochip 10 can be electrically connected with one or both of circuitry36 and 38 via the QP nodules 30 in contact with each other on microchips10 and 8, and/or microchips 10 and 6.

In other words, QP nodules 30 on different microchips that are incontact with each other can electrically connect electrical circuits onsaid microchips.

In FIGS. 1A and 1B, the material forming the body or substrate of eachmicrochip can also form the interconnecting structure or structures. Inan example, the first material (e.g., silicon) used to form the body ofmicrochip 4 can also form interconnecting structures 12 and 14; thematerial used to form the body of microchip 6 can also forminterconnecting structures 16 and 18; the material used to form the bodyof microchip 8 can also form interconnecting structures 20 and 22; andthe material forming the body of microchip 10 can also forminterconnecting structures 24 and 26.

Each interconnecting structure can be formed utilizing semiconductorfabrication processes and techniques well known in the art ofsemiconductor processing, e.g., photolithographic processing andetching, laser etching, and the like. However, this is not to beconstrued in a limiting sense. In an example, QP nodules 30 can beformed on each microchip in the manner disclosed in U.S. Pat. No.7,612,443 incorporated herein by reference.

With reference to FIGS. 2A and 2B, instead of microchips includinginterconnecting structures formed of the same material used to form thebodies of said microchips, in an example, the QP nodules 30 formed onthe microchips can be confirmed to have keyed complementary,interlocking shapes. In the example shown in FIGS. 2A and 2B, microchips42 and 44 can include QP nodules 30-9-30-14 having keyed complementary,interlocking shapes. In this example, QP nodules 30-9 and 30-10 can havekeyed complementary, interlocking L-shapes; QP nodule 30-11 can have aT-shape and QP nodule 30-12 can have a keyed complementary, interlockingT-shaped receiving slot 42, the latter of which can be that is formed bya pair of L-shaped QP nodules. Finally, QP nodules 30-13 and 30-14 can,like QP nodules 30-1 and 30-2, have keyed complementary, interlockingL-shapes.

The keyed complementary, interlocking interconnecting structures in theform of QP nodules 30-9 and 30-14 shown in FIGS. 2A and 2B, however, isnot to be construed in a limiting sense since it is envisioned thatmicrochips 42 and 44 can include any suitable and/or desirable form orshape of keyed complementary, interlocking shapes that enable QP nodulepairs 30-9, 30-10; 30-11, 30-12; and 30-13, and 30-14 to be used asinterconnecting structures.

With reference to FIGS. 3A and 3B, in another example, microchips 46 and48 can include any one or combination of interconnecting structures inthe form of QP nodule pairs 30-15, 30-16; 30-17, 30-18; and/or 30-19,30-20. In this example, the complementary shapes of the QP nodulesinclude curved or rounded projection 30-15 and curved or roundedreceiving slot 30-16; a stair-stepped projection 30-17 and a stair-stepreceiving slot 30-18; and/or a V-shaped projection 30-18 and a V-shapedreceiving slot 30-20.

The illustration in FIGS. 3A and 3B of different shaped projections andreceiving slots is not to be construed in a limiting sense since it isenvisioned that the same style QP nodule projection and QP nodulereceiving slot can be used a multitude of times on microchips 46 and 48.Moreover, the illustration in FIGS. 3A and 3B of microchip 46 includingone or more QP nodule structures including projections and microchip 48including one or more keyed, complementary QP nodule receiving slots isnot to be construed in a limiting sense since it is envisioned that eachmicrochip can include QP nodules having any suitable and/or desirablecombination of projections and keyed, complementary receiving slots.Further, the QP nodule projections and receiving slots on each microchipcan be the same or different shapes.

In the examples shown in FIGS. 1A-3B, the various complementary,interlocking shapes can be keyed to ensure the assembly of the variousinterconnecting structures and, hence, microchips, in only oneorientation. For example, in FIGS. 1A and 1B, interconnecting structure16 includes two different size/depth cavities, while the keyedcomplementary, interconnecting structure 12 includes complementary sizedprojections, wherein each projection of interlocking structure 12 isconfigured to be inserted in a correspondingly sized cavity ofinterlocking structure 16.

In the example shown in FIGS. 1A and 1B, each interconnecting structure12-26 can include a QP nodule 30 protruding beyond an edge of thecorresponding microchip. When the microchips are assembled in the formshown in FIG. 1B, each QP nodule protruding beyond an edge of onemicrochip can be in contact with an end or a side of a QP noduleextending from another microchip.

In the examples shown in FIGS. 2A-3B each interconnecting structure is aQP nodule itself versus the combination of a shape formed in the body ofmaterial forming a microchip and conventional QP nodules 30 formed onthe corresponding microchip.

With reference to FIGS. 4A-4C, an example non-planar substrate assembly2 including keyed complementary, interlocking structures will now bedescribed.

FIG. 4A (left) shows a top view of a microchip 50 that includes QPnodule sockets 56 and microchip sockets or cavities 60, and FIG. 4A(right) is a side view of a microchip 52 that includes substrateprojections 58 and recesses 64, and QP nodules 54 protruding beyond oneor more of said projections 58 and recesses 64.

FIG. 4B is a cross-section of microchips 50 and 52 assembled togethertaken along line IVB-IVB in FIG. 4A. As can be seen, when microchips 50and 52 are assembled in the manner shown in FIG. 4B, QP nodule 54-1protruding from an edge of recess 64 of microchip 52 is received in a QPnodule socket 56-1 formed in a top surface 66 of microchip 50.

FIG. 4C is a view of microchips 50 and 52 assembled together taken alonglines IVC-IVC in FIG. 4A. As shown in FIG. 4C, a projection 58 ofmicrochip 52 includes QP nodule 54-2 and microchip 50 includes acorresponding microchip socket or cavity 60, including a QP nodulesocket 56-2 for receiving QP nodule 54-2 protruding from an edge ofprojection 58 when projection 58 is inserted into microchip cavity 60.QP nodules 54 protruding beyond one or more edges of microchip 52 can beelectrically connected in a manner known in the art to circuitry formedon microchip 52. Similarly, each nodule socket 56 can be electricallyconnected in a manner known in the art to circuitry formed on microchip50. When microchips 50 and 52 are assembled in the manner shown in FIGS.4B-4C, circuits on microchips 50 and 52 can be electrically connectedvia the insertion of QP nodules 54 into nodule sockets 56.

As can be seen, in contrast to QP nodule 54-2 projecting from an edge ofprojection 58, QP nodule 54-1 projects from a recess 64 of microchip 52.

Microchip 52 including projections and recesses having QP nodules 54and/or microchip 50 including sockets 56 formed in a surface 66 and inmicrochip sockets 60 formed in surface 66 can be formed in any suitableand/or desirable manner. In an example, the combination of one or morerecesses 64, one or more projections 58, one or more QP nodules 54, oneor more nodule sockets 56 in a surface 66 of microchip 50, one or moremicrochip sockets 60, and one or more nodule sockets 56 in saidmicrochip sockets 60 can be formed in any suitable and/or desirablemanner that enables microchips 50 and 52 to be keyed for assembly in oneorientation.

For example, in the example shown in FIGS. 4A-4C, the interconnectingstructure of microchip 52 includes two projections 58 and three recesses64. Correspondingly, microchip 50 includes two microchip sockets orcavities 60 configured to receive the two projections 58 of microchip 52inserted therein. The projections 58 of microchip 52 includes quiltpackage nodules 54 that protrude from edges of said projections 58 andthe corresponding microchip sockets 60 of microchip 50 includecorresponding nodule sockets 56 configured to receive the quilt packagenodules 54 protruding from the edges or ends of projections 58 ofmicrochip 52 when said projections 58 are inserted into cavities 60.

The example shown in FIGS. 4A-4C is exemplary only and is not to beconstrued in a limiting sense since it is envisioned that microchips 50and 52 can be formed in any suitable and/or desirable manner to includeany combination of projections, recesses, microchip sockets, QP nodules,and/or nodule sockets as deemed suitable and/or desirable to ensure thatthe interconnecting structures on microchip 50 and the correspondinginterconnecting structures on microchip 52 are keyed to ensure assemblyof microchips 50 and 52 in only one orientation.

With reference to FIGS. 5A and 5B, FIGS. 5A-5B show respective top andside views of first and second microchips 68 and 70 including QP nodules72-1 and 72-2 of microchip 70 in spaced facing relationship with QPnodules 72-3 and 72-4 of microchip 68. In this example, each QP nodule72 projects, extends, or protrudes from a side surface of thecorresponding microchip. For example, QP nodules 72-1 and 72-2 protrudefrom a side surface 74 and edge of microchip 70, and QP nodules 72-3 and72-4 protrude from a side surface 76 and edge of microchip 68. As willbe described in further detail hereinafter, microchips 68 and 70 can beformed from the same microchip substrate. Each microchip 68 and 70 caninclude the same or different circuitry.

Each QP nodule 72 of each microchip can contact a QP nodules of anothermicrochip via end-to-end, face-to-face, or side-to-side contact of thesurfaces of the QP nodules. It is to be appreciated that QP nodules 72of microchip 68 and 70 are not necessarily moved into contact. Rather,the sides and/or faces 78 of the QP nodule 72 of each microchip 68 and70 can be joined in contact end-to-end, face-to-face, or side-to-sidewith a QP nodule of another substrate (not shown).

Having described microchips 68 and 70, a method of forming microchips 68and 70 with QP nodules 72 thereon will now be described with referenceto FIGS. 6A-6G.

Referring to FIG. 6A, in the method, a trench 80 can be formed in a topsurface of microchip substrate 82 utilizing semiconductor processingtechniques known in the art.

With reference to FIG. 6B and with continuing reference to FIG. 6A, nexta metal layer 84 can be formed on the bottom 86 and sides 88-1 and 88-2of trench 80, and on the top surface of microchip substrate 82 proximateto trench 80 in a manner known in the art, e.g., the Damascene process.

The portions of metal layer 84 on the top surface 90 of microchipsubstrate 82 can connect to circuitry 92 and 94 formed in or on thesurface of microchip substrate 82.

Next, as shown in FIG. 6C, a mask layer 96 can be formed on at least theexposed surfaces of metal layer 84. In an example, mask layer 96 can bea photoresist.

Next, as shown in FIG. 6D, via a mask (e.g., a photomask—not shown),mask layer 96 can be exposed to an appropriate wavelength of UV light,whereupon the portion of mask layer 96 on bottom 86 of trench 80 is (oris made) soft and soluble in the presence of a liquid developer and theremaining portions of mask layer 96 are hard (or remain hard) whereuponthese remaining portions are not capable of being washed away by thedeveloper.

Next, as also shown in FIG. 6D, the portions of mask layer 96 and metallayer 84 on the bottom 86 of trench 80 can be removed via appropriatedeveloper and etching solutions.

Thereafter, as shown in FIG. 6E the portion of microchip substrate atthe bottom 86 of trench 80 can be etched. In an example, the etching ofmicrochip substrate 82 at the bottom 86 of trench 80 can be anisotropicwhereupon the depth and width of the bottom of the trench increase(diverge) as shown in FIG. 6E. In another example, etching of microchipsubstrate 82 at the bottom 86 of trench 80 can be isotropic, as shown bydashed lines in FIG. 6E.

As shown in FIG. 6F, after etching trench 80 to increase its depth (asshown in FIG. 6E), mask layer 96 is removed leaving microchip substrate82 and metal layers 84. For the purpose of description, it will beassumed that an anisotropic etch is used to increase the depth and widthof the bottom of the trench to the shape shown in FIG. 6F.

Finally, as shown in FIG. 6G, the remaining material 98 at the verybottom of microchip substrate 82 is removed, e.g., via a backside grind,to produce microchips 68 and 70 having QP nodules 72-1 and 72-4 in theview shown in FIGS. 5A-5B.

As can be seen, disclosed herein is a substrate assembly that includesmicrochips formed to have keyed complementary, interlocking shapes. Inone example, the keyed complementary, interlocking shapes are formedfrom the substrate material forming each microchip and the electricalinterconnections between assembled substrates can be via QP nodulesformed along edges of each substrate.

In another example, the keyed complementary, interlocking shapes can beformed from the QP nodules themselves. Of course, combinations of keyedcomplementary, interlocking shapes formed from substrate material and QPnodules is envisioned. In another example, the keyed complementary,interlocking shapes can include nodule sockets and QP nodules ondifferent microchips. Each microchip in this example can include anynumber or combination of nodule sockets and QP nodules configured tomate with corresponding QP nodules and nodule sockets on the othermicrochip.

Finally, forming microchips with QP nodules 72 thereon is disclosed. Thesides and/or faces 78 of each said QP nodule 72 can be joined in contactend-to-end, face-to-face, or side-to-side with a QP nodule of anothersubstrate.

The examples have been described with reference to the accompanyingfigures. Modifications and alterations will occur to others upon readingand understanding the foregoing examples. Accordingly, the foregoingexamples are not to be construed as limiting the disclosure.

The invention claimed is:
 1. A method of forming a quilt package noduleon an edge of a microchip substrate comprising: (a) forming a trench ina microchip substrate, wherein the trench includes a bottom and firstand second sides; (b) following step (a), forming a metal layer on thebottom, the first and second sides of the trench, and on a top surfaceof the microchip substrate proximate the first and second sides; (c)following step (b), forming a mask layer on the exposed surfaces of themetal layer; (d) following step (c), removing portions of the mask andmetal layers on the bottom of the trench; (e) following step (d),etching the bottom of the trench to increase the depth of the bottom ofthe trench; (f) following step (e), removing remaining portions of themask layer from the surfaces of the metal layer, whereupon remainingportions of the metal layers on the first and second sides define quiltpackage nodules that protrude beyond edges of the first and secondsides; and (g) following step (f), removing the remaining portion of thetrench bottom thereby separating the first and second sides from eachother, whereupon each side includes at least one quilt package noduleprotruding from said side.
 2. The method of claim 1, wherein each sideincludes a plurality of quilt package nodules that protrude beyond theedge of said side.
 3. The method of claim 1, wherein the etching of step(e) forms an undercut between the metal layers on the first and secondsides and the bottom of the trench.